Maerua angolensis (PROTA)

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Plant Resources of Tropical Africa
Introduction
List of species


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Maerua angolensis DC.


distribution in Africa (wild)
1, flowering and fruiting branch. Source: Flore analytique du Bénin
Protologue: Prodr. 1: 254 (1824).
Family: Capparaceae

Vernacular names

  • Bead-bean, bushveld bead-bean, bead maerua (En).
  • Mutunguru, mlala-mbuzi, mkuruka (Sw).

Origin and geographic distribution

Maerua angolensis is widely distributed in continental tropical Africa but is absent in some countries with a high rainfall. It is also present in the northern parts of South Africa.

Uses

In Senegal powdered leaves are added to food to cure anorexia and asthenia. In Mali an extract of the stem bark is applied to wounds to promote healing. Elsewhere in Africa wounds, abscesses, sores and ulcers are treated with leaves or pulped leaves as a dressing, and leaf sap is sprinkled on or rubbed in with ground fruit. In Benin a decoction of leafy twigs is administered to children suffering from amoebic dysentery, and jaundice is treated by drinking a decoction of leafy twigs or used as a bath. In Sudan a decoction prepared from the stem bark is given twice a day to treat malaria. A leaf decoction is drunk as a cure for rheumatism. A decoction of the leaves or bark is taken to relieve stomach-ache. In Tanzania root and stem bark are used as an aphrodisiac, to cure diarrhoea and epilepsy. In Tanzania the powdered leaves are used as fish-poison.

In Ethiopia the leaves and tender parts are eaten as a vegetable and they are usually mixed with beans (Phaseolus spp.) or maize. People consume the leaves mainly in times of food shortages as the leaves are rather bitter. In Senegal the leaves are eaten as well, but use of the leaves as a condiment is more widespread. The foliage is considered in many countries as good forage, especially for sheep and goats but in other countries, including Gambia, it is considered poisonous. Honeybees feed on the flowers throughout the day. The wood is usually small-sized and used for mortars, tool handles, small furniture and posts. In Tanzania it was used to build canoes. It is not suitable for firewood but the wood is used to make charcoal. Maerua angolensis has been planted in West Africa as an ornamental and is very well suited for this purpose in areas with low rainfall.

Production and international trade

Dried leaves of Maerua angolensis are only traded in local markets.

Properties

A preliminary phytochemical screening of the methanolic extract of the stem bark revealed the presence of glycosides, tannins, saponins, terpenes, flavonoids, carbohydrates, proteins and alkaloids. The extract demonstrated an anti-diabetic effect in streptozocin-induced diabetic rats. The median lethal dose in rats is 3.8 g per kg body weight. Several C12, C14 and C18 fatty acids and esters that showed antifungal activity have been isolated from the aerial parts.

The wood is hard, heavy, fine-grained, yellowish and takes a fine polish.

Description

Shrub or small tree up to c. 10 m tall; branches usually pendulous, young branches dull brownish yellow, glabrous or rarely shortly pubescent, with white to cream lenticels. Leaves alternate, simple and entire; stipules bristly; petiole up to 3 cm long; blade (ovate-)lanceolate to elliptical, 3–10 cm × 1.5–5 cm, rounded or emarginated at apex, glabrous or pubescent. Inflorescence a short corymbose raceme, terminal or on short side branches or flowers solitary. Flowers bisexual, regular; pedicel 8–12 mm long; sepals 3–4, narrowly oblong-obovate to elliptical, 10–17 mm long, glabrous except margins; petals absent; stamens 50; ovary on a gynophore up to 4 cm long, narrowly cylindrical, 1-celled. Fruit a cylindrical capsule up to 22 cm long, constricted between the seeds, glabrous, few- to many-seeded. Seeds almost globose, c. 6 mm in diameter, pale brown, smooth.

Other botanical information

Maerua comprises c. 50 species, most of these in the drier areas of tropical Africa but some extending as well to the Middle East and tropical Asia. Maerua angolensis is very variable in its pubescence.

Maerua schinzii

In Zimbabwe and Botswana specimens with coarse hairs have been classified as Maerua schinzii Pax and Maerua schinzii might well be a subspecies of Maerua angolensis. In Namibia a decoction of the leaves of Maerua schinzii is drunk to cure coughs and is used as ear drops to relieve earache. The decoction is also used to wash the body to treat acne and other skin disorders, to improve the patient’s mood and just as a replacement for soap. The vapour of pounded leaves is inhaled to relieve headaches. The root is chewed as a tonic. Cardiac problems are treated in the same way and by wearing the root around the neck as an amulet or by eating the root ash. The fruit is sweet and drunk as a squash.

Maerua juncea

Maerua juncea Pax is a small shrub, straggler or liana distributed in the south-east of DR Congo, Tanzania, Malawi, Zambia, Namibia, Zimbabwe, Mozambique and South Africa. In Namibia a decoction of the roots is taken as an emetic. To induce vomiting after overeating the stems are chewed and the sap swallowed. The treat ulcers dressings with pounded leaves are applied. The foliage is browsed by livestock and game and the fruits are edible.

Growth and development

Young Maerua angolensis plants grow fast with an annual growth rate of up to 80 cm that diminishes with age to c. 50 cm. It produces abundant leaves in the dry season. Flowering starts when the plant is at least 3 years old. Flowering takes place at the end of the dry season and early in the rainy season. The tree produces vigorous suckers from its base after it has been damaged by bush fire.

Ecology

Maerua angolensis is widely spread in savannahs with a preference for sandy soils, from sea level up to 1500 m altitude. It is often found on termite mounds.

Propagation and planting

In most areas farmers do not plant it on purpose but spare it when they find a wildling in their fields. Only in southern and South Africa it is purposely multiplied and planted. It is easily cultivated from seed and fruits are easily collected in the wild. The fruit pulp has to be removed as it contains a growth inhibitor. Seed treatment does not improve germination. Seed is sown in flat trays filled with river sand and covered with a thin layer of sand or compost. Seeds should germinate within 12–20 days. Seedlings are transplanted into polybags filled with a mixture of sand, loam and compost (3:1:1).

Diseases and pests

The larvae of a number of butterfly species feed on the leaves. Instar larvae sometimes defoliate a tree completely. New leaves will grow again, sometimes already during the same season.

Harvesting

The leaves are harvested from the tree when needed.

Genetic resources

Although Maerua angolensis is widely distributed it is nowhere a common species and individual trees occur scattered. Even so, it is not likely to be threatened with genetic erosion.

Prospects

Further pharmacological evaluations of the stem bark of Maerua angolensis are required to identify and isolate the active antimalarial and hypoglycemic principles in the plant as well as elucidating their mechanisms of action.

Major references

  • Arbonnier, M., 2004. Trees, shrubs and lianas of West African dry zones. CIRAD, Margraf Publishers Gmbh, MNHN, Paris, France. 573 pp.
  • Burkill, H.M., 1985. The useful plants of West Tropical Africa. 2nd Edition. Volume 1, Families A–D. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 960 pp.
  • Kers, L.E., 2000. Capparidaceae. In: Edwards, S., Mesfin Tadesse, Demissew Sebsebe & Hedberg, I. (Editors). Flora of Ethiopia and Eritrea. Volume 2, part 1. Magnoliaceae to Flacourtiaceae. The National Herbarium, Addis Ababa University, Addis Ababa, Ethiopia and Department of Systematic Botany, Uppsala University, Uppsala, Sweden. pp. 74–120.
  • SEPASAL, 2012. Maerua angolensis. [Internet] Survey of Economic Plants for Arid and Semi-Arid Lands (SEPASAL) database. Royal Botanic Gardens, Kew, Richmond, United Kingdom. http://apps.kew.org/sepasalweb/sepaweb. Accessed Juni 2012.
  • Teketay, D., Senbeta, F., Maclachlan, M., Bekele, M. & Barklund, P., 2010. Edible wild plants in Ethiopia. Addis Ababa University Press, Addis Ababa, Ethiopia. 575 pp.
  • Wild, H., 1960. Capparidaceae. In: Exell, A.W. & Wild, H. (Editors). Flora Zambesiaca. Volume 1, part 1. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 195–245.

Other references

  • Akoègninou, A., van der Burg, W.J. & van der Maesen, L.J.G. (Editors), 2006. Flore analytique du Bénin. Backhuys Publishers, Leiden, Netherlands. 1034 pp.
  • Beentje, H.J., 1994. Kenya trees, shrubs and lianas. National Museums of Kenya, Nairobi, Kenya. 722 pp.
  • Bussmann, R.W., 2006. Ethnobotany of the Samburu of Mt. Nyiru, South Turkana, Kenya. Journal of Ethnobiology & Ethnomedicine 2: 35.
  • Coates Palgrave, K., 1983. Trees of southern Africa. 2nd Edition. Struik Publishers, Cape Town, South Africa. 959 pp.
  • Codd, L.E., Kers, L.E., Killick, D.J.B., Tölken, H.R. & Marsh, J.A., 1970. Capparaceae. In: Codd, L.E., de Winter, B., Killick, D.J.B. & Rycroft, H.B. (Editors). Flora of southern Africa. Volume 13. Botanical Research Institute, Department of Agricultural Technical Services, Pretoria, South Africa. pp. 118–177.
  • Diallo, D., Sogn, C., Samaké, F.B., Paulsen, B.S., Michaelsen, T. E. & Keita, A., 2002. Wound healing plants in Mali, the Bamako Region: an ethnobotanical survey and complement fixation of water extracts from selected plants. Pharmaceutical Biology 40(2): 117–128.
  • El-Kamali, H.H. & El-Khalifa, K.F., 1997. Treatment of malaria through herbal drugs in the Central Sudan. Fitoterapia 68(6): 527–528.
  • Elffers, J., Graham, R.A. & Dewolf, G.P., 1964. Capparidaceae. In: Hubbard, C.E. & Milne-Redhead, E. (Editors). Flora of Tropical East Africa. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. 88 pp.
  • Exell, A.W. & Mendonça, F.A., 1937. Capparidaceae. In: L. Wittnich Carrisso (Editor). Conspectus Florae Angolensis 1(1). Ministerio do Ultramar, Lisbon, Portugal. pp. 53–68.
  • Khan, M.R. & Nkunya, M.H.H., 1991. Antimicrobial activity of Tanzanian traditional medicinal plants. In: Mshigeni, K.E., Nkunya, M.H.H., Fupi, V., Mahunnah, R.L.A. & Mshiu, E.N. (Editors). Proceedings of an international conference on traditional medicinal plants, Tanzania, 18–23 February. Dar es Salaam University Press, Dar es Salaam, Tanzania. pp. 48–63.
  • Ki, R.N., 2005. Contribution à la multiplication de Saba senegalensis (A.DC.) Pichon par greffage et de Maerua angolensis (DC.) Pichon par semis. Ministère de l'Environnement et du Cadre de Vie, Rapport de stage. Ecole Nationale des Eaux et Forêts, Ouagadougou, Burkina Faso. 47 pp.
  • Latham, P., 2007. Plants visited by bees and other useful plants of Umalila, southern Tanzania. Third edition. P.Latham, DFID, United Kingdom. 216 pp.
  • Luo, X., Pires, D., Aínsac, J.A., Gracia, B., Mulhovo, S., Duarte, A., Anes, E. & Ferreira, M.-J.U., 2011. Antimycobacterial evaluation and preliminary phytochemical investigation of selected medicinal plants traditionally used in Mozambique. Journal of Ethnopharmacology 137: 114–120.
  • Mohammed, A., Tankyo, Y., Okasha, M.A., Sadiq,Y. & Esa, A.I., 2007. Effect of aqueous methanolic stem bark of Maerua angolensis (Capparidaceae) extract on blood glucose levels of streptozocin-induced diabetic Wistar Rats. Research Journal of Pharmacology 1(4): 75–78.
  • Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
  • UN-EUE, 2001. Typical 'famine-food' plants: Maerua angolensis. [Internet] Famine food field guide. United Nations Emergency Unit for Ethiopia, Addis Ababa, Ethiopia. http://www.africa.upenn.edu/faminefood/category1/cat1_Cadaba.htm. Accessed June 2012.
  • Van den Eynden, V., Vernemmen, P. & Van Damme, P., 1992. The ethnobotany of the Topnaar. University of Gent, Belgium. 145 pp.
  • von Koenen, E., 2001. Medicinal, poisonous and edible plants in Namibia. Klaus Hess Verlag, Göttingen, Germany. 336 pp.
  • von Maydell, H.-J., 1986. Trees and shrubs of the Sahel: their characteristics and uses. Schriftenreihe der GTZ No 196. Deutsche Gesellschaft für Technische Zusammenarbeit, Eschborn, Germany. 525 pp.

Sources of illustration

  • Akoègninou, A., van der Burg, W.J. & van der Maesen, L.J.G. (Editors), 2006. Flore analytique du Bénin. Backhuys Publishers, Leiden, Netherlands. 1034 pp.

Author(s)

  • H.H. El-Kamali, Botany Department, Faculty of Science and Technology, Omdurman Islamic University, P.O. Box 382, Omdurman, Sudan

Correct citation of this article

El-Kamali, H.H., 2013. Maerua angolensis DC. In: Schmelzer, G.H. & Gurib-Fakim, A. (Editors). Prota 11(2): Medicinal plants/Plantes médicinales 2. PROTA, Wageningen, Netherlands. Accessed 9 July 2021.